Electromagnetic shielding

ABSTRACT

A cable bushing is disclosed for placement into a control housing surrounding a printed circuit board that is provided with a bushing housing, comprising a locating surface, fasteners for fastening the bushing housing to the control housing, and retainers for at least two cables that are to be electrically connected to the printed circuit board. To facilitate the assembly of the cable bushing, a shielding plate is provided which embodies a shielding surface for contacting a shielding on the control housing side. The shielding surface is connected to a contact surface in an electrically conductive manner, and is exposed at a back of the bushing housing facing away from the locating surface to be connected to a shielding.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a cable bushing into a control housingsurrounding a printed circuit board. The cable bushing has, in a mannerknown per se, a bushing housing comprising a locating surface to abutagainst the control housing in a sealing manner, and preferablyfastening means for fastening the bushing housing to the controlhousing. Furthermore, the bushing housing includes retainers for atleast two cables to be electrically connected to the printed circuitboard.

2. Description of the Related Art

Such a cable bushing usually has a bushing housing formed of plastics oranother insulating material which is penetrated by retainers guiding thecable from the outside to the inside of the control housing. In priorart, the cable sheath of the cable within the bushing housing ispartially removed, for example to expose a shielding of the cable in theregion of the bushing housing and to electrically apply it to shieldcollars retained by the bushing housing and surrounding each cablecircumferentially. The bushing housing usually has a groove recessed inthe locating surface in which a sealing ring is inserted. Usually, acable seal is assigned to the retainers so that the cable may beintroduced into the control housing in a sealed manner to preventenvironmental influences, in particular moisture, from penetrating intothe control housing. The bushing housing furthermore comprises fasteningmeans, usually in the form of through-holes by which the bushing housingmay be fastened, in particular screwed, to the control housing.

Corresponding cable bushings are common in automotive engineering andmust meet the conditions all components installed in a vehicle areexposed to.

These include considerable thermal fluctuations, loads due to vibrationand dirt and moisture in the direct vicinity of those componentsprovided with a separate control system.

SUMMARY OF THE INVENTION

The present invention wishes to provide a cable bushing for an electricheating device in a motor vehicle. The present invention considers theproblem that such components are sometimes also installed in electricvehicles and operated at high voltages there. In this case, importanceis placed on the shielding to obtain optimal EMC-protection.

In the cable bushings known up to date, the cables are stripped insidethe control housing and provided with terminals connected to the wiresof the respective cables by crimping. These terminals must be connectedinside the control housing which involves assembly efforts. The cableslaid within the housing could moreover be squeezed during subsequentassembly operations within the control housing which can lead to cablebreaks. Furthermore, care must be taken high-voltage applications, thatthe electrically conductive parts of the cables are laid with sufficientdistances to other components. Moreover, air gaps and leakage pathswhich are to prevent any leakage current from flowing between thedifferent polarities have to be considered.

The previously known bushings do not fulfil these requirementssufficiently.

The object underlying the present invention is to provide an improvedcable bushing of the type mentioned in the beginning. Here, the cablebushing according to the invention is to facilitate the assembly of thecable bushing at a control housing, wherein both a facilitation of thecontacting between the individual cables and the conductors of theprinted circuit board and an easier contacting of a shielding are to beprovided.

To solve this problem with the present invention, a shielding plate issuggested which forms a shielding surface for contacting a shielding onthe control housing side which is, in an electrically conductive manner,connected to a contact surface which is exposed at a back of the cablebushing housing facing away from the locating surface to be connected toa shielding.

In the cable bushing according to the invention, the cable bushinghousing comprises, at its back facing away from the control housing, atleast one contact surface which may be connected to a shielding, inparticular a shielding braid, to electrically connect the shieldingsurface provided on the control housing side with the shielding suppliedfrom outside. Thus, the solution according to the invention offers theadvantage that cables not shielded individually may be guided throughthe cable bushing housing into the control housing, while the shieldingwhich encloses the entirety of cables guided through the cable bushinghousing in a shielding manner is maintained, without it being necessaryto provide each individual cable with a cable shielding.

The shielding on the control housing side is always realized by ashielding plate comprising a shielding surface for contacting ashielding on the housing side. The shielding plate contacts theshielding of the cable or an outer shielding of a loom of cablesaccommodating several individually insulated cables. The shieldingsurface serves the contacting with a shielding on the housing side. Thiscontacting may be accomplished, for example, by directly placing theshielding surface of the shielding plate against a mating surface of theshielding on the housing side. The shielding on the housing side may beformed, for example, by a surface of a metallic control housing or ashielding incorporated in the control housing, which may be introducedinto a housing wall of the control housing, for example, by coating withplastics, while it is exposed in the region of the shielding surface.

Preferably, the contact elements are held by the bushing housing suchthat they protrude from a front face of the bushing housing and areembodied to be adapted for plug contacting with the printed circuitboard and are electrically connected to the associated cables within thebushing housing. The cable bushing according to the invention may becorrespondingly governed by the idea that a plug contact between thecables to be connected and the printed circuit board may be directlyaccomplished via the cable bushing. The contact elements are hereusually received in associated female plug contact elements which may bemounted on the surface of the printed circuit board, or they areprovided inside the printed circuit board as is described in EP 2 236330 and EP 2 897 230 A1, respectively. As a printed circuit board in thesense of the present invention, any plate-like, i.e. flat structure, isconsidered which is provided with electrically conductive paths. Theprinted circuit board may be equipped with components. However, it mayalso not be provided with corresponding components and only be embodiedto be adapted for grouping heating circuits or for conducting controlcurrent and power current in one plane of the control housing. As aprinted circuit board in the sense of the present invention, a printedcircuit board as it is described in EP 2 505 931 A1 may be considered.Such a printed circuit board basically consists of a plurality of busbars held in an insulating frame. In this embodiment, too, the femaleplug contact elements are usually produced directly by punching andbending those strips forming the conductive paths of the stripconductor.

It will be appreciated that the bushing housing is preferably connectedto the control housing in the solution according to the invention, too.For this, too, the bushing housing according to the invention preferablycomprises bores for a threaded joint between the control housing and thebushing housing.

If the female plug contact elements are mounted on the surface of theprinted circuit board and protrude from it, a mating surface assigned tothe printed circuit board is usually provided against which the frontface of the bushing housing abuts to fix it relative to the printedcircuit board by abutment against the same. However, an embodiment wherethe front face directly abuts against the printed circuit board ispreferred where accordingly the female plug contact elements areprovided in the plane of the printed circuit board or on the back of theprinted circuit board with respect to the cable bushing. In this case,the surface of the printed circuit board may be directly used forpositioning and holding the bushing housing within the control housing.

Correspondingly, the front face of the bushing housing is usuallyembodied to be adapted for direct abutment against the printed circuitboard. The front face may correspondingly have contours adapted to thecontour of the printed circuit board. Preferably, the front face haspositive locking elements cooperating with positive lockingcounter-elements of the printed circuit board to cause a poka-yokefunction so that the bushing housing may be positioned relative to theprinted circuit board only in one unique manner, and the individualcontact elements may be contacted with the associated contactcounter-elements of the printed circuit board.

The embodiment according to the invention usually requires that thefront face is provided, in the extension direction of the cables, at adistance to the locating surface, since the printed circuit board isnormally arranged at a distance to a housing wall of the control housingwhich is penetrated by the cable bushing and against which the cablebushing is mounted.

The front face of the bushing housing is preferably provided at adistance to a flange which forms, according to a preferred furtherdevelopment of the present invention, the locating surface and ispreferably provided with a circumferential groove recessed in thelocating surface and accommodating a sealing ring. The flange may beformed by a part of the bushing housing supporting the contact elements.However, the flange may also be formed by a bushing part of the housingthrough which the cables are guided in a sealed manner and which isformed separate of a retainer part which supports the contact elementsand forms the front face. The bushing part itself may be formed by anelastic material to permit an optimal sealing of the cable and/or withrespect to the housing wall of the control housing. If the nature of thematerial of the bushing part is appropriate, a separate sealing ring maybe omitted, in particular if the bushing part is formed of flexibleplastics. The bushing housing is usually completely manufactured as aplastic component as a molded plastic part.

Preferably, at least one electrically insulating web extending betweentwo contact elements protrudes from the front face. The latter isusually monolithically formed to the bushing housing. The correspondingweb enlarges the leakage path and provides an air gap between thecontact elements protruding from the front face. The web is usuallyreceived in a web retainer of the printed circuit board providedcorresponding to it, whereby the leakage current path between the twocontact elements is increased also in the region of the printed circuitboard. This web retainer acts as a positive locking counter-element tothe web and may correspondingly have a poke-yoke function. Preferably, aplurality of webs protrudes from the front face and preferably extendbetween the respective contact elements and require, apart from theabove-described function of increasing the air gaps and leakage paths,moreover a unique spatial association of the bushing housing relative tothe printed circuit board to create an electric contact between thecontact elements and the corresponding strip conductors of the printedcircuit board.

Preferably, the shielding surface is formed by a shielding plate whichcomprises at least one contact web protruding from the shielding surfaceby punching and bending the sheet material, the contact web beingexposed at a circumferential surface of the cable bushing housing andcooperating with a shielding placed externally against the bushinghousing with a shielding braid. To this end, the cable bushing housingpreferably includes a housing projection which protrudes over a locatingflange at the back, whereby a locating surface for the shielding braidis formed. The shielding braid is correspondingly pushed externally overthe cable bushing housing, especially the housing projection, and placedagainst the outer circumference of the cable bushing housing therebyenclosing and directly contacting the contact web or webs.

The flange and the housing projection are preferably monolithicallybuilt at the cable bushing housing which preferably consists of twocomponents, that is a bushing housing body comprising the flange and thehousing projection, and a housing cap which is provided in view of abetter sealing of the cables within the bushing housing body. Thisimproved sealing is preferably caused by latching the housing cap withthe bushing housing body. However, it is possible to achieve a sealingin another manner so that the cable bushing housing according to theinvention may also be monolithically made of one single molded part.

In the preferred embodiment mentioned above, the bushing housing bodyincludes passages extending from the front face to the back face andassigned to the contact elements. These passages form contact retainersat a front side which are embodied to be adapted for receiving thecontact elements. At the back of the passages, sealing retainers, eachcooperating with a cable sealing element, are provided. The cablesealing elements usually cooperate with a sheath of the cable, whereby asecure sealing between the cable sheath and the bushing housing body isachieved which prevents the penetration of dirt or moisture into thecontrol housing.

In view of the above discussed preferred development, the housing capincludes projections engaging the sealing retainer of the bushinghousing body and cooperating with the cable sealing element received inthe sealing retainer. Thereby, the sealing effect is increased asdescribed above. The housing cap may preferably be latched with thebushing housing body to create a simple mechanical connection.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details and advantages of the present invention can be takenfrom the following description of exemplified embodiments in connectionwith the drawing, wherein the first exemplified embodiment servesillustration purposes, and only the second exemplified embodiment is anexample according to the present invention. In the drawings:

FIG. 1 shows a perspective side view of a first exemplified embodiment;

FIG. 2 shows a plan view onto the front side of the first exemplifiedembodiment;

FIG. 3 shows a perspective side view of a shielding element of the firstexemplified embodiment;

FIG. 4 shows a perspective side view of a contact element of the firstexemplified embodiment;

FIG. 5 shows a longitudinal sectional view of the first exemplifiedembodiment;

FIGS. 6a to 6i show perspective side views of different assembly stepsin the manufacture of the first exemplified embodiment;

FIG. 7 shows a perspective side view of a second exemplified embodiment;

FIG. 8 shows a perspective plan view onto the housing cap of the secondexemplified embodiment;

FIG. 9 shows a perspective plan view onto the bushing housing body ofthe second exemplified embodiment;

FIG. 10 shows a perspective plan view onto the shielding plate of thesecond exemplified embodiment;

FIG. 11 shows a plan view onto the front side of the second exemplifiedembodiment;

FIG. 12 shows a longitudinal sectional view of the second exemplifiedembodiment along line XII-XII according to FIG. 11;

FIGS. 13a to 13j show perspective side views of different assembly stepsin the manufacture of the second exemplified embodiment, and

FIG. 14 shows a sectional representation along line XIV-XIV according tothe representation in FIG. 11 for a cable bushing with a control housingelement.

DETAILED DESCRIPTION

FIG. 1 shows a perspective side view of an exemplified embodiment of acable bushing housing 2 for a cable bushing according to the invention.The cable bushing housing 2 is in the present case embodied in twopieces and has a bushing part 4 and a retainer part 6 which areconnected to each other with the interposition of a shielding plate 8.The bushing part 4 forms a flange 10 which forms a locating surface 12for placing it against a not represented control housing. The locatingsurface 12 is provided with a circumferential groove 14 into which asealing ring 16 is inserted.

The shielding plate 8 shown in a perspective view in FIG. 3 has severalbores penetrating a flat shielding surface 18 of which one central boreis designated with reference numeral 20. The lateral bores designatedwith reference numeral 22 are shaped as female plug element retainers.The lateral fastening bores provided on the opposite side and designatedwith reference numeral 24 are penetrated by tappets that penetrate thelocating surface 12 and are provided at the bushing part 4 and/or theretainer part 6, and they are fitted in associated bores of therespective other part to position both parts 4, 6 relative with respectto each other while enclosing the shielding plate. By this positivelocking, a pre-positioning of the shielding plate 8 relative to one ofthe parts 4 or 6 may be effected to pre-assemble the shielding plate 8at one of the parts 4, 6 and to then join the two parts 4, 6.

The shielding plate 8 forms two crimp webs 26 extending essentially atright angles to the shielding surface 18 and formed by punching andbending out of the initially flat material of the shielding plate 8.During this sheet processing, crimp lugs are moreover formed whichprotrude at right angles from the oblong crimp webs 26. Below, theindividual crimp lugs will be discussed which are to this purposedesignated with reference numeral 28 (first crimp lug), 30 (second crimplug), and 32 (third crimp lug).

Reference numeral 34 designates a male contact element in FIG. 4 whichforms a contact tongue 36 at its front end. At the end opposite to thecontact tongue 36, the contact element 34 has inner crimp lugs 38 andouter crimp lugs 40. Between this end of the contact element 34 on thefastening side and the contact tongue 36, a latching tongue 42 is cutfree by punching and bending and bent out of the plane of the sheetmaterial forming the contact element 24.

FIGS. 1, 2 and 5 show further details of the exemplified embodiment. Thecontact elements 34 obviously protrude, with their free ends, i.e. thecontact tongues 36, from a front face 44 of the retainer part 6 andcorrespondingly form male contact elements for plug contacting the cablebushing housing 2 with a printed circuit board. Between the two contacttongues 36, in the longitudinal direction of extension of the contactelements 34 corresponding to the direction of extension of cables 46which are each connected to the contact elements 34, webs 48 extendwhich are monolithically embodied at the retainer part 6 and protrude,in the longitudinal direction of extension, from the contact elements 4(cf. FIG. 5). Between these two webs 48, the front face 44 is penetratedby a central bore 50 in which a clamping pin 52 is exposed which isprovided monolithically at the bushing part 4 and projects through thelocating surface 12. The clamping pin 52 is seated in a clamping pinretainer 54 which is recessed at the retainer part 6. The clamping pin52 may be pressed on or glued within this clamping pin retainer 54.Equally, the clamping pin 52 made of plastic may be fixed in theclamping pin retainer 54 by warm caulking. To this end, the bore 50 hasan essentially larger diameter than the clamping pin retainer 54 or theclamping pin 52.

At the opposite end of the cable bushing housing 2, there are, on asheath 56 of the respective cables 46, elastomeric cable sealingelements 58 with an outer labyrinth seal. The inner diameter of thecable sealing elements 58 is adapted to the outer diameter of the cablesheath 56. In the joined state according to FIG. 5, the labyrinth seal,i.e. the sealing rings of the cable sealing element 58 provided with adistance, abut against an outer sealing surface 60 which is formed bythe bushing part 4 and is provided adjacent to a cable bushing opening62 at the rear end of the bushing part 4. The outer sealing surface 60is conically broadened towards the retainer part 6 and passes over intoa retainer space 64 for one of the crimp webs 26 each. In this receivingspace 64, the cable 46 is connected to the shielding plate 8. To thisend, the second crimp lugs 30 enclose the cable with its sheath 56circumferentially. The first crimp lugs 28 circumferentially abutagainst a cable shielding 66 which is exposed by removing the cablesheath 56 and is protruded by an inner sheath 68 in the longitudinaldirection of the cable 46 which surrounds an electrically conductivewire 70 of the cable. This wire 70 is also electrically connected withthe inner crimp lug 38 by crimping. The outer crimp lugs 40 enclose theinner sheath 68 for the mechanical connection and tension relief betweenthe contact element 34 and the associated cable 46. The third crimp lugsprovided in pairs each enclose one sleeve section of the cable sealingelement 58 which is provided upstream of the labyrinth seal in the axialdirection and monolithically at the cable sealing element 58. Thereby,the cable sealing element 58 is fixed on the cable sheath 56 in theaxial direction.

Below, the assembly of the exemplified embodiment is illustrated withreference to FIGS. 6 a-j. First, the retainer part 6 is shifted over thecables 56 (FIG. 6a ). Then, the cable sealing elements 58 are eachshifted over the free ends of the cables 46 (FIG. 6b ). Then, tubingpieces designated with reference numeral 72 are each pulled over thecable 56 from the free end (FIG. 6c ). The free ends of the cables 46are stripped to expose, on the one hand, the cable shielding 66 and,with an axial distance thereto, the wire 70 (FIG. 6d ).

Then, the respective contact elements 34 are shifted over the free endsof the cables 46 and connected to them mechanically and electrically bycrimping. This situation is represented in FIG. 6e . For a simplerrepresentation, the outer and inner crimp lugs 38, 40 are stillrepresented as protruding. It will be appreciated that at the end of theassembly, all crimp lugs will abut against a circumferential section ofthe cable 46 to be connected.

Then, the shielding plate 8 is connected to the cables 46. The secondcrimp lug 30 is placed against the cable sheath 56 as tension relief,the first crimp lug 28 is placed against the cable shielding 66 asshielding connection. In the course of said crimping, the third crimplugs 32 remain in their original state (cf. FIG. 6f ).

Now, the tubing pieces 72 are shifted up to the central piece of theshielding plate 8 forming the shielding surface 18 and shrunk onto it.Then, the tubing piece 72 covers the first crimp lugs 28 and the secondcrimp lugs 30 (FIG. 6g ). The cable sealing elements 58 are now shiftedalong the cables 46 towards the shielding plate 8 until the labyrinthsealing basically abuts against the third crimp lugs 32. The third crimplugs 32 are crimped to axially fix the cable sealing element 58 on thecable 46 (FIG. 6h ).

Due to the shielding plate 8 and the positioning by the crimp webs 26,the cables 46 and thus the contact elements 34 are pre-positionedrelative with respect to each other. Thus, the retainer part 6 may beshifted, after a single positioning relative to the shielding plate 8,over the contact elements 34 which are introduced into contact retainers74 recessed at the retainer part 6 in the process. During this movement,the latching tongue 42 latches against a mating surface of the retainerpart 6 so that the contact elements 34 and thus the cables 46 areconnected to the retainer part (FIG. 6i ). Finally, the bushing part 4is shifted, guided by the cables 46, against the retainer part 6 andplaced against it. In the process, the clamping pin 52 first penetratesthe central bore 20 of the shielding plate 8 and is finally received inthe clamping pin retainer 54 of the retainer part 6 and fastened therein the manner as described above, for example by warm caulking (FIG. 6i, FIG. 5). Finally, the sealing ring 16 is inserted into the groove 14.

In the finished product according to FIGS. 1, 3 and 5, the female plugelement retainers 22 of the shielding plate 8 are located within thesealing ring 16 and outside a circumferential surface which is formed bythe retainer part 6. Thereby, the shielding of the cable bushing housing2 formed by the shielding plate 8, which is connected to the cableshielding 66 in an electrically conductive manner, may be plug-contactedwithin the control housing or at the same. It is also possible toprovide contacting tappets at the outer side of the control housingwhich engage, when the bushing housing 2 is being fitted, thecorresponding female plug element retainers 22 and are connected to themin an electrically conductive manner.

In the direction of extension of the webs 48 in front of and behind thebore 50, preparations 76 are visible in FIG. 6a which are provided atthe bushing part 4 to guide further cables, apart from the two cables 46provided for the power current, for example cables of an HV interlock,within the cable bushing housing 2 inwards into the control housing.These HV interlock cables, too, are preferably provided in the form ofmale plug elements protruding from the front face 44 of a retainer partfacing away and may thus be connected to the printed circuit board by apin-and-socket connection.

The exemplified embodiment according to FIG. 7 et seqq., shows acorresponding embodiment.

In the exemplified embodiment according to FIG. 7 et seqq., a cablebushing housing 102 is formed by a housing cap 104 and a unitary bushinghousing body 106 which are latched in the mounted state. The bushinghousing body 106 supports a shielding plate 108 via a flange 110monolithically formed at the bushing housing body 106 from the frontface of which a housing projection 109 protrudes whose front face isprotruded by webs 111 (FIG. 13h ). The flange 110 forms a locatingsurface 112 to be placed against a control housing. This locatingsurface 112 is provided with a groove 114 which accommodates a sealingring 116 which is provided within the shielding plate 108 (FIG. 7). Tothis end, a shielding surface designated with reference numeral 118 ispenetrated by a central recess 120 which exposes the sealing ring 116 inthe locating surface 112 (cf. FIG. 10). Moreover, the shielding plate108 includes punched out holes 122 penetrating the shielding surface 118which, in the mounted state, are aligned with lateral fastening bores124 which represent examples of fastening means in the sense of theinvention and are recessed at the flange 110 (cf. FIGS. 9, 10). Fourcontact webs 126, which essentially extend at right angles to theshielding surface 118, are bent out of the plane containing theshielding surface 118 by punching and bending. The outer side of thecontact web 126 here forms a contact surface 126.1. To locate thecontact webs 126, the housing projection 109 is provided with locatingwebs 125 which protrude from the convex circumferential surface of thehousing projection 109 and are protruded by latching cams 127 (FIG. 9).

The housing cap 104 shown in FIG. 8 comprises projections 129 protrudingforward from a cover surface 128 which are each slightly resilientlybound to the cover surface 126 and being assigned to major openings 130within the cover surface. Between these major openings 130, the coversurface 128 is furthermore penetrated by minor openings 131. A collar132 of the housing cap 104 has, distributed at the periphery, fourlatching openings 133 in which in the joined state the latching cams 127are latched; cf. FIG. 12.

The contact elements of the second exemplified embodiment are embodiedto be identical with the contact elements of the first exemplifiedembodiment and are altogether designated with reference numerals 134,135 and, with respect to their details, with reference numerals 136 to142. Reference is made to the description to FIG. 4.

The bushing housing body 106 is made of an insulating plastic materialand has four passages penetrating the bushing housing body 106 from thefront to the back of which the major passages are designated withreference numerals 144, and the minor passages are designated withreference numeral 145. At the back visible in FIG. 9, the passages 144,145 are embodied as sealing retainers which are designated in FIGS. 9and 11 as large sealing retainers 146 and small sealing retainers 147.These sealing retainers 146, 147 are embodied to be adapted forreceiving large and small cable sealing elements 148, 149 adapted interms of size. The respective cable sealing elements 148, 149 have alabyrinth sealing structure with several axially spaced apart sealingbeads. They are made of a flexible material. Their inner diameters areadapted to the outer diameter of a cable of which the cables conductingthe power current are designated with reference numeral 151, and thecables assigned to the HV interlock circuit are designated withreference numeral 152. The large contact elements 134 are connected tothe HV power cable 151, the small contact elements 135 to the HVinterlock cable 152. The cables 151, 152 have a cable sheath 156, 158and a wire 160. In the present exemplified embodiment, they have noseparate cable shielding.

As is illustrated in FIG. 11, the passages 144, 145 each have at thefront side contact retainers 162 adapted for receiving the contactelements 134, 135.

The small contact retainers designated with reference numeral 164 areassigned to the contact elements 135 to the HV interlock cables 152.These contact elements 166 are essentially embodied like the contactelements 134 and have inner and outer crimp lugs and a latching tonguepunched free for locking in the bushing housing body 106. In thisrespect, too, reference can be made to the description of the contactelements 134.

In the mounted state, the projections 129 engage the large sealingretainers 148 and cooperate with the cable sealing elements 152 providedthere to press them within the sealing retainer 148 and increase thesealing effect. Such measures are not required for the sealing of thesmall cable sealing elements 149.

To assemble the exemplified embodiment, first the housing cap 104 isshifted over the cables 151, 152 (FIG. 13a ). Then, the cable sealingelements 148, 149 are shifted over the cables 151, 152 (FIG. 13b ). Now,the contact elements 134, 135 are connected to the cable sheath 156 ofthe respective cables 151, 152 mechanically via the outer crimp lug 140,and electrically via the inner crimp lug 138 by crimping (FIG. 13c ).The contact elements 134, 135 are now shifted into the bushing housingbody 106 (FIG. 13d ). Then, the housing cap 104 is latched with thebushing housing body (FIG. 13e ). From the opposite front side, theshielding plate 108 is now guided over a housing projection 109 of thebushing housing body 106 protruding from the flange 110 (FIG. 13f ). Inthe process, the contact webs 126 penetrate contact web retainers 170recessed at the flange 110 and are finally exposed at the outerperiphery of the housing projection 109 distributed on the periphery(cf. FIGS. 12, 13 f). The shielding surface 118 essentially covers thelocating surface 112 which is formed by the flange 110. The groove 114remains open due to the central recess 120 (FIG. 13g ). Now, the sealingring 116 may be inserted (FIG. 13h ). Finally, a shielding braiddesignated with reference numeral 172 is pulled over the housingprojection 109 so that the inner periphery of the shielding braid 172encloses the contact webs 126 (FIG. 13i ). A cable fastener designatedwith reference numeral 174 fixes the shielding braid 172 against thehousing projection 109 while enclosing and electrically contactingbetween the shielding braid 172 and the contact webs 126. Thus, ashielding guided from the outside to the inside is provided within thecable bushing housing 2 (FIGS. 12, 13 j). At the other end of theshielding braid 172, an electric plug for plug contacting the controlhousing which is shielded while enclosing the shielding braid 172 may beprovided.

In the mounted state, the contact elements 134, 135 protrude from thefront face of the housing projection 109. The webs 111 extend betweenthe contact elements 134 for the HV power current.

FIG. 14 shows a sectional view along line XIV-XIV according to therepresentation in FIG. 11 for the above described cable bushing in caseof an assembly to a control housing element designated with referencenumeral 180 which is embodied as a metallic housing shell. The controlhousing element 180 has several supporting cams 184 protruding from aninner surface 182 which are usually provided in corner regions of thecontrol housing element 180 and support a printed circuit board 186which is equipped with various components 190. The control housingelement 180 furthermore forms at least one cooling projection 192against which abuts a circuit breaker 194 generating stray power,normally with the interposition of an electrical insulation layer, thecircuit breaker 194 being contacted via the printed circuit board 186.

The printed circuit board 186 has several recesses 196 which areequipped with female contact elements 198 which have spring tonguesprojecting into the recess 196 and are described in EP 2 236 330 A1. Viathese female contact elements 198, the small and large contact elements134, 135 are contacted with the printed circuit board 186. To this end,the respective contact elements 134, 135 are—as is demonstrated in FIG.14—inserted through the recess 196 and project through the printedcircuit board 186.

In the shown exemplified embodiment, the printed circuit board 186 islocated at a small distance to the front face of the housing projection109. The arrangement of the printed circuit board 186 with respect tothe size of the control housing element 180 is selected such that thecorresponding gap is observed when the flange 110 abuts against an outersurface 200 of the control housing element 180 with the interposition ofthe shielding surface 118, whereby the outer shielding of the cable istransferred via the shielding braid 172 to a control housing shieldingformed by the metallic control housing element 180.

The control housing element 180 has a groove 202 surrounding at the freeedge into which a projection of a housing lid may be introduced that canbe placed onto the control housing element 180 in a sealing manner. Viaan elastic adhesive introduced in the groove 202, a sealing to thehousing lid may be achieved so that the printed circuit board 186 isaccommodated in the control housing and protected from environmentalinfluences.

What is claimed is:
 1. A cable bushing for placement into a controlhousing surrounding a printed circuit board, comprising: a bushinghousing comprising a locating surface, fastening means for fastening thebushing housing to the control housing, retainers for at least twocables which are to be electrically connected to the printed circuitboard, and a shielding plate embodying a shielding surface forcontacting a shielding on a side of the control housing, wherein theshielding surface is connected to a contact surface in an electricallyconductive manner, wherein the contact surface is exposed at a back ofthe bushing housing facing away from the locating surface at an outercircumference of the bushing housing to be connected to a shielding. 2.The cable bushing according to claim 1, wherein contact elementsprotrude from a front face of the bushing housing, are adapted for plugcontacting with the printed circuit board and are electrically connectedto an associated cable within the bushing housing.
 3. The cable bushingaccording to claim 2, wherein the shielding surface is formed by ashielding plate which comprises at least one contact web protruding fromthe shielding surface, the contact web being formed from the shieldingplate by punching and bending and being exposed at a circumferentialsurface of the bushing housing for forming the contact surface andcooperating with a shielding braid that is externally placed against thebushing housing.
 4. The cable bushing according to claim 3, wherein thebushing housing forms a flange that is monolithically providedtherewith, wherein a front side of the flange supports the shieldingsurface of the shielding plate and a back side of the flange isprotruded by the at least one contact web and a housing projection,wherein the housing projection is monolithically formed at the bushinghousing, and against which the shielding abuts with the interposition ofthe contact web.
 5. The cable bushing according to claim 3, whereinseveral contact webs are distributed about a periphery of the housingprojection.
 6. The cable bushing according to claim 1, wherein theretainers comprise passages that extend from a front face to a back faceof a monolithic bushing housing body and that are assigned to thecontact elements, and wherein the contact elements each form, at a frontface thereof, and contact retainers adapted to receive the contactelements, and wherein, at a back thereof, sealing retainers are adaptedto receive a cable sealing element cooperating with a sheath of a cable.7. The cable bushing according to claim 6, wherein a housing cap islatched with the bushing housing body, the housing cap formingprojections which engage a sealing retainer of the bushing housing bodyand which cooperate with the cable sealing element received in thesealing retainer.
 8. A control device in a motor vehicle, of an electricheating device, comprising: a control housing surrounding a printedcircuit board which is equipped with female plug contact elements, and abushing housing comprising: a locating surface, fastening means forfastening the bushing housing to the control housing, and retainers forat least two cables which are electrically connected to contactelements, wherein the contact elements are held in the bushing housingand are electrically contacted with the printed circuit board.
 9. Thecontrol device according to claim 8, further comprising a shieldingplate which embodies a shielding surface contacting a shielding on aside of the control housing, wherein the shielding surface is connectedto a contact surface in an electrically conductive manner, and whereinthe contact surface is exposed at a back of the bushing housing facingaway from the locating surface at the outer circumference of the bushinghousing to be connected to a shielding.
 10. The control device accordingto claim 9, wherein the shielding surface is formed by a shielding platethat comprises at least one contact web protruding from the shieldingsurface, the contact web being formed from the shielding plate bypunching and bending and being exposed at a circumferential surface ofthe bushing housing for forming the contact surface and cooperating witha shielding braid that is externally connected against the outercircumference of the bushing housing.
 11. The control device accordingto claim 10, wherein the bushing housing forms a flange which ismonolithically provided there, wherein a front side of the flangesupports, the shielding surface of the shielding plate, and wherein aback side of the flange is protruded by the at least one contact web anda housing projection, wherein the housing projection is monolithicallyformed at the bushing housing, and against which the shielding abutswith the interposition of the contact web.
 12. The control deviceaccording to claim 10, wherein several contact webs are distributedabout the periphery of the housing projection.
 13. The control deviceaccording to claim 8, wherein the retainers comprise passages thatextend from a front face to a back face of a monolithic bushing housingbody and that are assigned to the contact elements, and wherein thecontact elements each form contact retainers at a front face thereofthat are adapted to receive the contact elements, and wherein, at a backthereof, sealing retainers are adapted to receive g a cable sealingelement cooperating with a sheath of the cable.
 14. The control deviceaccording to claim 13, wherein a housing cap is latched with the bushinghousing body, the housing cap forming projections which engage in asealing retainer of the bushing housing body and which cooperate withthe cable sealing element received in the sealing retainer.